conditions in ocean models

As an alternative to the frequently used mixed boundary conditions in ocean GCM’s, we present a dynamic atmospheric model (ECBILT) that is simple and yet describes the relevant dynamic and thermodynamic feedback processes to the ocean. This provides the possibility of studying atmosphere/ocean dynamics on very long time-scales of the order of a thousand years. The model is two orders of magnitude faster than AGCMs. We have been running ECBILT with prescribed SSTs for a period of 500 years with seasonal cycle included both in the solar forcing and in the climatological SSTs. The mean state and the variability properties of ECBILT are reasonably realistic. The simulation of the surface fluxes is quite realistic and justifies coupling ECBILT to an ocean GCM. We have done two SST anomaly experiments, one with a tropical SST anomaly as observed during January 1983 and one with an SST anomaly in the northern extra-tropical Atlantic ocean. For the tropical SST anomaly experiment the amount of anomal-ous precipitation agrees well with what has been found with atmospheric GCM’s, but the resulting extra-tropical teleconnection pattern is very weak. The atmospheric response pattern to extra-tropical SST anomalies agrees well with similar SST anomaly experiments performe